This invention relates generally to multilayer liquid absorption and deformation devices. More particularly, it relates to such devices for medical purposes and most particularly it relates to self-expandable intraluminal vascular stents employing such devices wherein the liquid is water.
In some embodiments, the stents may be biodegradable or they may be capable of releasing therapeutic drugs or they may be capable of doing both simultaneously.
Biodegradable and drug releasing stents and other medical devices are not new in the art as evidenced, for example, by the following patents: U.S. Pat. No. 5,306,250 to March et al. on Apr. 26, 1994; U.S. Pat. No. 5,443,458 to Eury et al. on Aug. 22, 1995; U.S. Pat. No. 5,443,495 to Buscemi et al. on Aug. 22, 1995; U.S. Pat. No. 5,464,450 to Buscemi et al. on Nov. 7, 1995; U.S. Pat. No. 5,500,013 to Buscemi et al. on Mar. 19, 1996 and Japanese patent application J63-9715 8 A, published Apr. 27, 1988.
U.S. Patent No. 5,389,106 to Tower on Feb. 14, 1995 describes a stent having an impermeable polymer membrane disposed inside a wire frame. However, the membrane is not biodegradable.
Devices making use of water swellable material, some of which are stents, are described in U.S. Pat. No. 4,460,642 to Errede et al. on Jul. 17, 1984; U.S. Pat. No. 4,496,535 to Gould et al. on Jan. 29, 1985; U.S. Pat. No. 4,872,867 to Joh on Oct. 10, 1989; U.S. Pat. No. 5,163,952 to Froix on Nov. 17, 1992; U.S. Pat. No. 5,234,456 to Silvestrini on Aug. 10, 1993; U.S. Pat. No. 5,258,020 to Froix on Nov. 2, 1993; U.S. Pat. No. 5,464,419 to Glastra on Nov. 7, 1995; U.S. Pat. No. 5,554,180 to Turk on September 1996; EP patent 0502905B1 on Sep. 14, 1994 and EP patent 0441516B1 on Mar. 29, 1995. None of these patents make use of swellable material in the manner of this invention nor for the same purpose.
The content of all of the above-identified patents are incorporated herein by reference.